I know how people are getting mixed experiences with whether this is a voluntary update or not. The answer is in the ps3-updatelist.txt. In America where the update is not compulsory they have this ps3-updatelist.txt:

The "CompatibleSystemSoftwareVersion" tells the ps3 the minimum version it can be on to access SEN. And if you have a look at the American one it is 4.10, but for Australia it is 4.11. If you don't believe me, test it out on a proxy.